High performance integrated circuit (IC) packages are well known in the art. Improvements in IC packages are driven by industry demands for increased thermal and electrical performance and decreased size and cost of manufacture.
In general, array packaging such as Plastic Ball Grid Array (PBGA) packages provide a high density of interconnects relative to the surface area of the package. However, typical PBGA packages include a convoluted signal path, giving rise to high impedance and an inefficient thermal path which results in low thermal dissipation performance. With increasing package density, the spreading of heat generated by the package is increasingly important.
Reference is made to FIG. 1, which shows an elevation view of a conventional PBGA package indicated generally by the numeral 20. The PBGA package 20 includes a substrate 22 and a semiconductor die 24 attached to the substrate 22 by a die adhesive. Gold wire bonds 26 electrically connect the die 24 to metal traces on the substrate 22. The wire bonds and die 24 are encapsulated in a molding compound 28. Solder balls 30 are disposed on the bottom surface of the substrate 22 for signal transfer. Because of the absence of a thermal path away from the semiconductor die 24, thermal dissipation in this package is poor.
Variations to conventional BGA packages have been proposed for the purpose of increasing thermal and electrical performance. One particular variation includes the addition of a metal heat spreader to the package, as shown in FIG. 2 which shows an elevation view of a PBGA package 20 of the prior art including the heat spreader, indicated by the numeral 32. In general, the metal heat spreader is fixed to the molded package. This package suffers disadvantages, however, as heat must be dissipated from the semiconductor die 24, through the molding compound 28 and then through the heat spreader 32.
It is therefore an object of an aspect of the present invention to provide a process for manufacturing a BGA package with a heat spreader that obviates or mitigates at least some of the disadvantages of the prior art.